Mechanical diodes, e.g., selectable one-way clutches (SOWCs) are frictionless engagement clutches that selectively produce a mechanical connection between a driving member and a driven member, and may be advantageously applied in a powertrain system to effect torque transfer between rotating elements, e.g., within a gearbox of a transmission. Known mechanical diodes preferably include a first coupling plate coupled to a driving member and a second coupling plate attached to a driven member, and a selector plate. The first and second coupling plates may be locked together, i.e., engaged to transfer torque in one or both rotational directions, and may also be capable of overrunning in one or both rotational directions under certain operating states, depending on its particular design.
The mechanical devices that are used to lock the first and second coupling plates may include rollers, sprags, rockers, struts, or other suitable torque-transmitting elements, a plurality of which are positioned in races formed in the first and second coupling plates. Depending on the particular type or style of mechanical diode and the required direction of rotation and torque holding, each race may contain unique surface features, such as pockets, windows or strut wells that are suitable for engaging one or more of the torque-transmitting elements positioned therein in order to selectively enable various clutch operating modes.